The present invention relates to saw bars for use with a chain saw, and more particularly, the invention relates to an improved saw bar which facilitates oiling of the chain and removal of sawdust which collects in the bar.
A chain saw is provided with a guide bar that is utilized to support the moving cutting chain that performs the cutting action, and generally, there is a groove around the outer edge of this guide bar which contains the cutting chain. When the chain saw is in use, there is a great tendency for this groove to fill with sawdust and, if the groove is left uncleaned, the sawdust will eventually cause the chain to jam in the groove. Therefore, it is necessary to frequently stop cutting in order to clean the accumulated sawdust out of the groove so that the chain can continue to move smoothly and uninterrupted by the sawdust.
While it is recongized that sawdust accumulation in the groove is a serious problem, very few improvements have been provided to eliminate the problem. One improvement, however, is presented in U.S. Pat. No. 3,829,971 to Anderson. In this patent, numerous alternating holes are formed in the guide bar on opposite sides of the guide groove at the end of the bar extending from the motor chassis. These holes allow the sawdust to be "kicked out" of the groove before it has a chance to accumulate. This structure, unfortunately, requires numerous holes to be formed in the portion of the guide bar that receives the greatest external force, and the thus-weakened bar can have a shorter, safe working life span, and of course, the structure required much additional machining to provide all of the holes.
Another frequent problem which plagues the free and uninterrupted use of a power chain saw is the constant plugging of the oil lubricating holes which lubricate the moving chain within the guide groove. Nearly all chain saws, especially those which are used commercially and receive constant use, have these lubricating holes. For the most part, the holes are formed in the guide bar transverse to the guide groove and the holes are communicated with a lubrication supply or supply means in the chassis of the saw which provides a lubricating oil to the chain in the guide groove through these holes. Because of the transverse orientation of these holes, however, they are very susceptible to being filled and eventually clogged with sawdust, and thus, oil is prevented from reaching the chain. The saw must then be stopped and the holes cleaned of sawdust before cutting can continue.
In an effort to overcome these problems, several patents have been obtained on guide bar structures which have altered dramatically the configuration of the lubricating holes: Arff et al., U.S. Pat. Nos. 3,777,401 and 3,840,991, and Gorski, U.S. Pat. No. 3,870,125. While these patents disclose interesting new design features for the lubricating holes, they require intricate machining and, moreover, the designs are not readily adaptable to the numerous guide bars which are already provided with simple straight, transverse lubricating holes.